This invention concerns a valve for a system having an energy-carrying medium which flows through a number of energy exchangers in the system, said valve having a thermostat valve with a housing comprising an inlet and an outlet, a spindle with a seal which can be displaced by a thermostat bellows and which, depending on the expansion/contraction of the thermostat bellows and against the force of a spring which surrounds the spindle, can respectively close and open an opening with a seating in a transverse wall in the housing between the inlet and the outlet.
The plant may for example be a circulation plant where the fluid medium after being heated gives off energy to or after being cooled takes up energy from the surroundings or to/from a secondary fluid medium through at least one energy exchanger or a similar object. Such plants are generally called heating plants or cooling plants (air-conditioning), respectively.
A central heating plant with a similar valve is known from U.S. Pat. No. 5,178,324, said plant being configured in such a manner that it is possible to control the flow in the entire plant, a single part of the plant or in several zone-divided sections of the plant.
This plant comprises several energy exchangers each provided with its own valve, said energy exchangers being intended to be placed in a number of at least one in each room in a building, and where the valves are disposed in the piping of the plant.
In central energizing plants it is important that the water is distributed through the plant in a pre-calculated proportion so that the dimensioned energy requirements of the individual energy exchangers are taken into consideration.
It is also important that the energy-carrying liquid remains in the energy exchangers for a period of time which is long enough to allow a reasonable amount of energy to be dissipated in the rooms of the building which are to be energized by the energy exchangers, which can be ensured by means of a differential pressure valve placed in the individual branches of the plant, in that this valve can regulate the flow of the energy-carrying fluid.
Furthermore, it is important that the differential pressure across the individual energy exchangers is so low that noise does not arise in the valves, in that such noise can cause inconvenience, either directly or by transmission through the piping system.
In the individual rooms, the flow of energy-carrying liquid through the energy exchanger or each of the energy exchangers can be controlled by means of thermostatic valves which, depending on the temperature in the room, can open more or less to allow flow through the energy exchanger(s) so that the emission of energy to the rooms can be held within those limits which are determined by the accuracy of the thermostatic valves, and by the temperature which the user of the room desires to maintain by the adjustment of the thermostatic valve or valves.
When ordinary thermostatic valves are mounted in a length of piping which leads the energy-carrying medium from a energy exchanger to the subsequent energy exchangers, each of these thermostatic valves will be dependent on the others. Thus if ten thermostatic valves are mounted in a length of piping, and nine of these are closed, the differential pressure across the open valve will be increased. This results in an increase in the flow through the associated energy exchanger, and the increased flow can also give rise to disturbing noise.
This situation can arise, for example, at times of the year when the incidence of sunlight makes energizing unnecessary. If there is also opened a window in that room in which the open thermostatic valve is mounted, the associated energy exchanger will receive a considerably greater flow than would otherwise be the case.
It is also difficult to achieve a mutual balance between the individual pipes in the building, the reason being that the flow will change depending on the differential pressure. Today, this drawback is overcome by providing each length of piping with an extra valve which is carefully adjusted to ensure the balance between the individual pipes.